1. Field of the Invention
The present invention relates generally to the field of telescoping sliding panels, and more specifically to a panel track and panel carriages with interlocking lips which prevent the panels from being pushed or lifted out of the track.
2. Description of the Prior Art
There have long been sliding door security devices which block the doors from sliding open. These devices, however, are generally not designed to prevent the doors from being pushed out of their track.
One such anti-sliding device is disclosed in Blough, U.S. Pat. No. 4,379,576, issued on Apr. 12, 1983. Blough teaches a fixed bracket which bolts to one door and presents a horizontal lip with a hole in it. A pivoting bracket is attached to an end of the adjacent door which rotates down to present a horizontal surface resting on top of the lip. A hole is provided in this surface directly over the hole in the lip, so that a bolt or padlock can be inserted through them. In addition to preventing sliding, the bolt or padlock incidently prevents one door from being lifted away from the adjacent door at the point they are joined. This structure, however, does not prevent the doors from being lifted together out of their track or pivoted relative to each other. Also, Blough requires the inconvenience of removing and reinserting the bolt or lock each time the doors are opened.
Another anti-sliding device is illustrated in Stevens, U.S. Pat. No. 4,248,461, issued on Feb. 3, 1981. Stevens discloses a long, spring-loaded plate having a series of ratchet-shaped vertical catches. A tab projects from the door adjacent to the plate and engages the catches. Pressing down on an end of the plate releases the tab so that the adjacent door can slide to a new position. Then the plate is released and the nearest catch engages the tab and secures the door against further sliding. Stevens thus permits the door to be secured in a variety of positions. A problem with Stevens, as noted above, is that it does not prevent the doors from being lifted off their track and pushed open. Although the ratchet apparatus by chance blocks one side of one door, the door can still be pushed out in the other direction.
An anti-sliding device for a screen door is described in Kelly, U.S. Pat. No. 4,284,299, issued on Aug. 18, 1981. Kelly discloses a handle which bolts onto a vertical edge of a screen door, having a spring-loaded lip which snaps into the door frame. The vertical section of the door frame is a channel which might prevent lateral movement of the door when closed within it. Yet this frame only secures an end of the door at best, and does not prevent it from being lifted off and pivoted out of its track.
Guardia, U.S. Pat. No. 4,763,933, issued on Aug. 16, 1988, discloses an anti-sliding mechanism for a sliding door which telescopes with a fixed door. Guardia has a rotary knob-operated bolt on an end of one door which engages a slot on the other door to keep the doors from sliding relative to each other. In addition to the rotary bolt feature, Guardia provides a latch feature which also prevents relative sliding. The latch projects from the knob assembly into a catch on the other door. The knob assembly pivots away from the catch to release the latch. Although Guardia prevents one door from sliding relative to the other, it does not prevent them from being lifted up and out of their track.
An anti-sliding mechanism providing multiple bolts is taught in Logas, U.S. Pat. No. 4,643,005, issued on Feb. 17, 1987. A key mechanism simultaneously operates two hook bolts and two straight bolts, joined together by linkages. Holes are provided for the straight bolts to permit them to lock the door in the closed position, or in a partly open position. A problem with Logas is that it only secures the door at one end, so that it could conceivably still be lifted and pivoted out of its track.
A security device to prevent sliding doors from being lifted out of their track is taught in Gist, U.S. Pat. No. 4,526,412, issued on July 2, 1985. Gist teaches a clip which snaps onto the track. The clip is a channel which fits over an edge of the track, having an inwardly curved wall to grip the track. The other wall of the channel is bent outward at a right angle and extends over the top of the door, blocking upward movement. A problem with Gist is that the clip could fall out of the track while the door is open. Gist also provides no retaining means to block a door from being pushed or kicked out of its track, apart from the happenstance structure of the track itself.
Several design patents which pertain to window frames are also found in the prior art. These include Dallaire, U.S. Design Pat. No. 216,955, entitled Extruding Sliding Window Member, issued on Mar. 24, 1970; Dallaire, U.S. Design Pat. No. 226,374, entitled Extruded Plastic Header Track for a Window Unit, issued on February 1973; Dallaire, U.S. Design Pat. No. 250,352, entitled Window Component Extrusion, issued on Nov. 21, 1978; and Mauro, U.S. Design Pat. No. 250,843, issued on Jan. 16, 1979. None of these design patents appears to teach a mechanism to lock a sliding door or window against being lifted or pushed out of its track.
It is thus an object of the present invention to provide a device which locks sliding panels against being lifted or pushed out of their track, as may result from an attempted burglary or a high wind.
It is another object of the present invention to provide such a device which secures the doors along a greater extent than a single point.
It is finally an object of the present invention to provide such a device which is inexpensive, easy to install and reliable.